For an equivalent caloric intake, low-carb and low-fat diets yield very similar results.
Quick answer
No, not in themselves. Given an equivalent energy intake, low-carb and low-fat diets produce very similar long-term results. What causes weight gain is the total amount, not the food category.
TL;DR
"I cut out bread and pasta, so that's the problem, right?"
This is currently the most widespread nutritional belief, having replaced the one that blamed fats thirty years ago.
The fact that the "guilty" category has changed once should already encourage caution.
Direct comparisons show only minor differences.
Dozens of trials have compared low-carb diets to low-fat diets. Over six to twenty-four months, the former shows an advantage, but it remains modest—around one kilogram. Beyond two years, the difference disappears.
One or two kilos over two years is not what popular belief suggests.
The initial loss is misleading.
When you drastically reduce carbohydrates, your body depletes its glycogen stores. Each gram of glycogen holds about three grams of water, so you quickly lose one to three kilos in the first few days.
It’s real on the scale, but it isn't fat. This rapid loss explains much of the initial enthusiasm for these diets—and the equally rapid regain as soon as carbohydrates are reintroduced.
Why these diets still work for some people.
Eliminating an entire food category mechanically reduces your total intake. You stop eating bread, pasta, rice, and pastries—so you end up eating less.
Furthermore, protein and fat have a significant satiating effect, which helps reduce appetite without conscious effort.
This mechanism is not unique to carbohydrates. It is simply one of many ways to eat less.
The debate is not entirely settled.
To be honest, some researchers argue that the composition of your diet influences energy expenditure beyond just the total calorie count, and this hypothesis is the subject of serious study. However, the reported effects remain modest and are far from justifying the idea that a specific food causes weight gain regardless of what else you eat.
On the other hand, not all carbohydrates are created equal. A serving of legumes and a pastry have neither the same energy density nor the same effect on satiety. The useful question is not whether you eat carbohydrates, but which ones and in what quantity.
A struggling company does not turn itself around by cutting an entire budget line.
It can do so, and it will have an immediate effect. But if the problem is that total spending is too high, cutting the travel budget without looking at the rest only shifts the difficulty—and deprives the company of something that was serving a purpose.
What matters is the total and how it is distributed. Not the elimination of a category.
Those who cut out carbohydrates often see quick results, only to find themselves hitting a wall.
The initial weight loss is dramatic, which reinforces the belief. Then it stops, because what was left to lose was fat, and that does not disappear at the same rate. At that point, the person concludes they weren't strict enough and cuts even more.
The second problem appears later: these diets are socially difficult to maintain. Refusing bread, starches, and desserts in a professional setting where you eat out regularly is exhausting. Most people give up within a few months.
Those who achieve lasting results have almost all done the opposite. They kept the carbohydrates, adjusted the quantities, and prioritized sources that actually keep them full.
Eliminating a food category works as long as you can stick to it. Adjusting quantities works for as long as you live.
Do not eliminate an entire category. A framework that bans entire food groups will not survive your social life.
Look at the total before the composition. That is what determines the direction you are heading.
Choose carbohydrates that keep you full. Legumes, whole grains, potatoes, and fruit. In equal amounts, they keep you satisfied much longer than sugary or refined products.
If a low-carb diet works for you, stick with it. There is nothing dangerous about it, and it works well for some people. Just be aware that its effectiveness comes from the total intake, not any specific property.
Don't draw any conclusions from the first few days. What you lose during that time is mostly water.
For any questions related to diabetes or metabolic conditions, please consult your doctor. Your relationship with carbohydrates then becomes a medical matter, not a question of methodology.
No single food causes weight gain. An excessive total intake does.
This article describes general mechanisms and does not constitute individual nutritional advice.
Meta-analysis comparing low-carb and low-fat diets across 33 studies and nearly 4,000 participants, Frontiers in Nutrition, 2022 DIETFITS trial and associated re-analyses Literature on glycogen storage and water retention